Separate Cross Sections Research Articles

Evaluation of apical extrusion of debris and centering ability in different nickel-titanium files during curved root canal preparation

BackgroundCurved root canals lead to difficulties in cleaning, shaping and filling the root canal system. Apical extrusion of debris and root canal transportation are important factors causing postoperative complications. In clinical practice, commonly selected instruments include multifile NiTi systems, such as M3-Pro PLUS (M3-PRO), Orodeka Plex 2.0 (ODP), Rotate (ROT), and Protaper Gold (PTG), as well as single-file NiTi systems, such as M3-L Platinum 2019 (M3L), Waveone Gold (WOG), and Reciproc Blue (RCB). This study aimed to comprehensively evaluate the differences in the apical extrusion of debris and centering ability of the above NiTi files.MethodsSeventy 3D-printed resin teeth were used (n = 10). The apically extruded debris was collected in a preweighed centrifuge tube. The resin teeth with or without root canal preparation were cut into separate cross sections at 1 mm, 3 mm, 5 mm, and 7 mm away from the root apex, and then the root canal transportation and centering ratio of each cross section were calculated.ResultsApical extrusion of debris was highest in RCB but lowest in OD-P (P < 0.05). Root call deviation was lowest in ROT at the 3 mm level, in PTG at the 5 mm level, and in PTG and ROT at the 7 mm level (P < 0.05). The centering ratio of NiTi files was highest in the RCB group at the 3 mm level, in the PTG group at the 5 mm level, in the ROT group at the 7 mm level (P < 0.05).ConclusionsFor NiTi files with the same system, the cross-sectional design is the greatest factor affecting the extrusion of debris, and motion mode is the second. In addition, the multifile system could reduce the degree of root canal transportation.

Extraction Method of Microscopic Image Feature of Cotton Fiber Cross Section

The micro-section image analysis is an effective method to measure cotton fiber maturity directly. However, the accuracies of the existing image segmentation and contour extraction algorithms were limited by the extraction of cotton fiber cross-section features. Therefore, the paper first binarized the cotton fiber cross-section micro image with the image processing software programmed by VC++, and then extracted the contours of its outer layer, inner layer and cavity, and finally calculated its geometric features. Based on statistics of these geometric features, a judgment model was established to remove the low quality cross sections such as pseudo-cross sections and separate adhesion cross sections, so as to improve the geometric feature extraction effect and the maturity estimation accuracy of cotton fiber cell. The results showed that, compared with the artificial subjective judgment, the cotton fiber cross-section feature extraction method proposed in this paper could not only solve the problem of unable to determine the geometric characteristics caused by cotton fiber adhesion and other interference factors, but also reduce the identification error rate from 0.073 to 0.038, so as to better judge the quality of cotton fiber at harvest time, and infer the possible influencing factors.

Two-photon-exchange effects in ep→enπ+ and their corrections to separated cross sections σL,T,LT,TT at small −t

In this work, the two-photon-exchange (TPE) effects in $ep\rightarrow en\pi^+$ at small $-t$ are discussed within a hadronic model. Under the pion dominance approximation the TPE contribution to the amplitude can be described by a scalar function in the limit $m_e\rightarrow 0$. The TPE contributions to the amplitude and the unpolarized differential cross section are both estimated when only the elastic intermediate state is considered. We find that the TPE corrections to the unpolarized differential cross section are about from $-4\%$ to $-20\%$ at $Q^2=1$--$ 1.6$ GeV$^2$. After considering the TPE corrections to the experimental data sets of unpolarized differential cross section, we analyze the TPE corrections to the separated cross sections $\sigma_{\textrm{L,T,LT,TT}}$. We find that the TPE corrections (at $Q^2=1$--$1.6$ GeV$^2$) to $\sigma_{\textrm{L}}$ are about from $-10\%$ to $-30\%$, to $\sigma_{\textrm{T}}$ are about $20\%$, and to $\sigma_{\textrm{LT,TT}}$ are much larger. By these analysis, we conclude that the TPE contributions in $ep\rightarrow en\pi^+$ at small $-t$ are important to extract the separated cross sections $\sigma_{\textrm{L,T,LT,TT}}$ and the electromagnetic magnetic form factor of $\pi^+$ in the experimental analysis.

Electron capture by fast projectiles from lithium, carbon, nitrogen, oxygen and neon

The three-body boundary-corrected continuum intermediate state method is used to compute total cross sections for single charge exchange in ion-atom collisions at intermediate and high impact energies. Detailed illustrations are given for several scattering systems: H+ + Li, He2+ + Li, H+ + C, He2+ + C, H+ + N, H+ + O and H+ + Ne, He2+ + Ne. An independent particle model and the frozen-core approximation are employed with only one target electron taken as being active. The initial ground state of the active electron in a multi-electron target is described by five wave functions. These are two Roothaan-Hartree-Fock (RHF) wave functions, the single- as well as double-zeta functions and the hydrogen-like functions. Comparisons among the resulting cross sections are made to check their sensitivity to the choice of the initial target wave functions. In the case of a lithium target, the separate cross sections for electron capture from the K-shell and L-shell are reported. The present theoretical total cross sections are compared with the available experimental data and overall good agreement is found, especially when using the RHF wave functions for multi-electron targets.

Diamond slicing using ultrashort laser-induced graphitization and additional nanosecond laser illumination

Single-crystal diamonds exhibit properties consistent with semiconductor substrates. However, they are hard and brittle, making them difficult to slice. Therefore, this study demonstrates diamond slicing by applying femtosecond laser internal processing, which converts diamond to graphite. Additionally, the use of nanosecond lasers for further modification is also demonstrated. This method enables diamond slicing with only a small kerf loss. A femtosecond laser beam (pulse energy of 2 μJ, pulse duration of 550 fs) was tightly focused using an objective lens with a numerical aperture (NA) of 0.5. The focus was scanned parallel to the optical axis towards the light source (i.e., backward). The scanning speed was set to 100 μm/s. A continuous modified line of 12–15 μm diameter was formed in the diamond. In addition, adjacent single lines were formed with a spacing of 5 μm, and a planar modified layer (15–20 μm thick) was generated in the bulk diamond. The differences in crystal orientation in the texture of the modified layer were also clarified.In addition, the first modified layer was reheated using a nanosecond pulsed laser to convert it into a separable layer. A diamond of size approximately 1 × 1 mm2 was separated, and the separated surface and cross section were observed. Furthermore, the separation of the diamond depended on a crack generated in the front of the modified layer during additional laser illumination. Raman spectroscopy showed that the modified layer contained graphite.

Meson Form Factors and Deep Exclusive Meson Production Experiments

Pion and kaon electroproduction data play a unique role in Nature and our understanding of them is essential for explaining hadron structure. Precision longitudinaltransverse separated pion and kaon cross sections are of particular interest. They allow for the extraction of meson form factors and validation of understanding of hard exclusive and semi-inclusive reactions (π+ , K + , π0 , γ ) towards 3D hadron imaging and potential future flavor decomposition. We review recent data and present prospects for deep exclusive pion and kaon electroproduction at the 12 GeV Jefferson Lab including the prospects to use projected charged- and neutral pion data to further determine the spin, charge-parity and flavor of GPDs, including the helicity-flip GPDs.

Neutron cross sections for carbon and oxygen from new R-matrix analyses of the13,14C and17O systems

We report the latest results from R -matrix analyses of reactions in the 13,14 C and 17 O systems that are of interest in reactor applications and nuclear astrophysics. These were done in order to provide separate cross sections for the stable isotopes (12,13 C) of natural carbon, and to contribute improved cross sections for 16 O to the CIELO project. Although particular attention was paid to the data in the standards region ( +16 O, the analyses extend to several MeV neutron energy for all the systems. The fits to the data included are generally quite good, in keeping with the unitary constraints of R -matrix theory. The cross sections for 12,13 C give results for natural carbon that are close to the previous evaluation by Fu et al. at energies below 1 MeV. Above that energy, the deviations become larger, especially near the narrow resonances. The thermal cross section for 16 O is at the upper end of the range of recommended values, in excellent agreement with a high-precision measurement by Schneider. At higher energies, the 17 O analysis follows in great detail high-resolution measurements of the total cross section, and agrees quite well with the 13 C(α,n)16 O cross section measurement of Bair and Haas at roughly their original normalization scale. We will discuss the implications of these new evaluations for critical benchmarks and astrophysical applications.

Fragmentation of anthracene C₁₄H₁₀, acridine C₁₃H₉N and phenazine C₁₂H₈N₂ ions in collisions with atoms.

We report experimental total, absolute, fragmentation cross sections for anthracene C14H10, acridine C13H9N, and phenazine C12H8N2 ions colliding with He at center-of-mass energies close to 100 eV. In addition, we report results for the same ions colliding with Ne, Ar, and Xe at higher energies. The total fragmentation cross sections for these three ions are the same within error bars for a given target. The measured fragment mass distributions reveal significant contributions from both delayed (≫10(-12) s) statistical fragmentation processes as well as non-statistical, prompt (∼10(-15) s), single atom knockout processes. The latter dominate and are often followed by secondary statistical fragmentation. Classical Molecular Dynamics (MD) simulations yield separate cross sections for prompt and delayed fragmentation which are consistent with the experimental results. The intensity of the single C/N-loss peak, the signature of non-statistical fragmentation, decreases with the number of N atoms in the parent ion. The fragment intensity distributions for losses of more than one C or N atom are rather similar for C14H10 and C13H9N but differ strongly for C12H8N2 where weak C-N bonds often remain in the fragments after the first fragmentation step. This greatly increases their probability to fragment further. Distributions of internal energy remaining in the fragments after knockout are obtained from the MD simulations.

Charged-pion electroproduction above the resonance region

[Background] Above the nucleon resonance region, the $N(e,e'\pi^\pm)N'$ data cannot be explained by conventional hadronic models. For example, the observed magnitude of the transverse cross section is significantly underestimated in a framework with Reggeized background amplitudes. [Purpose] Develop a phenomenological framework for the $N(e,e'\pi^\pm)N'$ reaction at high invariant mass $W$ and deep photon virtuality $Q^2$. [Method] Building on the work of Kaskulov and Mosel, a gauged pion-exchange current is introduced with a running cutoff energy for the proton electromagnetic transition form factor. A new transition form factor is proposed. It respects the correct on-shell limit, has a simple physical interpretation and reduces the number of free parameters by one. [Results] A study of the $W$ dependence of the $N(e,e'\pi^\pm)N'$ lends support for the newly proposed transition form factor. In addition, an improved description of the separated and unseparated cross sections at $-t \lesssim 0.5 \;\text{GeV}^2$ is obtained. The predictions overshoot the measured unseparated cross sections for $-t > 0.5 \;\text{GeV}^2$. Introducing a strong hadronic form factor in the Reggeized background amplitudes brings the calculations considerably closer to the high $-t$ data. [Conclusions] Hadronic models corrected for resonance/parton duality describe the separated pion electroproduction cross sections above the resonance region reasonably well at low $-t$. In order to validate the applicability of these models at high $-t$, separated cross sections are needed. These are expected to provide a more profound insight into the relevant reaction mechanisms.

Intensity of in‐lake processes in floodplain lakes within the Bug River zone of fluvial activity

AbstractThe paper presents a new approach to calculating the erosion and deposition values of floodplain lake basins, the erosion–deposition index (EDI). The EDI is a sum of the basin geometry indices (BGIs), which can be calculated for a separate cross section of the lake. The distribution of processes within the basin was investigated in two selected floodplain lakes with the use of BGIs. Field research was carried out in the Bug River valley from 1 November 2006 to 31 October 2011. The highest erosion was observed in the lakes located close to the parent river. Deposition processes were observed in lakes with high inflow of groundwater. The results showed that EDI values of 48 out of the 71 floodplain lakes ranged from −0.2 to 0.2. Spatial distribution of erosion and deposition processes within the lake basins resulted from a velocity of water inflowing or flowing through the basin. This was observed especially in contrafluent–confluent lake. Inflow of rivers water via upstream crevasse occurred later than via downstream one, but energy of flowing water was higher, which favoured erosion of this part of the lake basin. Copyright © 2013 John Wiley &amp; Sons, Ltd.

Assessment of spectral history influence on PWR and WWER core

Abstract The few-group cross section libraries, used by reactor dynamics codes, are affected by the spectral history effect – a dependence of fuel cross sections not only on burnup, but also on local spectral conditions during burnup. Neglecting this effect leads to an additional component of error in neutron-physical characteristics. Two solution approaches to this problem implemented in the reactor dynamic code DYN3D are described and compared in this paper: a cross section correction method based on239Pu concentration and separate cross sections treatment for each axial layer of reactor core. Steady-state and burnup characteristics of a PWR and a WWER-1000 cores, calculated by DYN3D with and without cross section corrections, are compared. An impact of the correction on transient calculations is studied for a control rod ejection example. Studies have shown a significant influence of spectral history on axial power and burnup distributions as well as on calculated cycle length. Two different correction methods have shown similar major effects.

Importance of work environments on hospital outcomes in nine countries.

To determine the effect of hospital work environments on hospital outcomes across multiple countries. Primary survey data using a common instrument were collected from separate cross sections of 98 116 bedside care nurses practising in 1406 hospitals in 9 countries between 1999 and 2009. Nurse burnout and job dissatisfaction, patient readiness for hospital discharge and quality of patient care. High nurse burnout was found in hospitals in all countries except Germany, and ranged from roughly a third of nurses to about 60% of nurses in South Korea and Japan. Job dissatisfaction among nurses was close to 20% in most countries and as high as 60% in Japan. Close to half or more of nurses in every country lacked confidence that patients could care for themselves following discharge. Quality-of-care rated as fair or poor varied from 11% in Canada to 68% in South Korea. Between one-quarter and one-third of hospitals in each country were judged to have poor work environments. Working in a hospital with a better work environment was associated with significantly lower odds of nurse burnout and job dissatisfaction and with better quality-of-care outcomes. Poor hospital work environments are common and are associated with negative outcomes for nurses and quality of care. Improving work environments holds promise for nurse retention and better quality of patient care.

Spin–spin coupling edition in chiral liquid crystal NMR solvent

The application of the G-SERFph pulse sequence is presented on enantiomeric mixtures dissolved in a chiral liquid crystal. It aims at editing, within one single 2D spectrum, every proton coupling which is experienced by a given proton site in the molecule, and leads to real phased T-edited spectroscopy ( T = J + 2 D). This NMR experiment is based on the combination of homonuclear semi-selective refocusing techniques with a spatial frequency encoding of the sample. This approach, which consists in handling selectively each coupling in separate cross sections of the sample, is applied to the visualization of enantiomers dissolved in a chiral liquid crystalline phase. Advantages and limits of this methodology are widely discussed.

Empirical fit to precision inclusive electron-proton cross sections in the resonance region

An empirical fit is described to measurements of inclusive inelastic electron-proton cross sections in the kinematic range of four-momentum transfer $0\ensuremath{\leqslant}{Q}^{2}&lt;8$ GeV${}^{2}$ and final-state invariant mass $1.1&lt;W&lt;3.1$ GeV. The fit is constrained by the recent high-precision longitudinal and transverse separated cross section measurements from Jefferson Lab Hall C, unseparated Hall C measurements up to ${Q}^{2}$ $\ensuremath{\approx}7.5$ ${\mathrm{GeV}}^{2}$, and photoproduction data at ${Q}^{2}=0$. Compared to previous fits, the present fit covers a wider kinematic range, fits both transverse and longitudinal cross sections, and features smooth transitions to the photoproduction data at ${Q}^{2}=0$ and deep inelastic scattering data at high ${Q}^{2}$ and $W$.

Cross sections and Rosenbluth separations inH1(e,e′K+)Λup toQ2=2.35 GeV2

The kaon electroproduction reaction 1H(e,e'K+)Lambda was studied as a function of the virtual-photon four-momentum, Q2, total energy, W, and momentum transfer, t, for different values of the virtual- photon polarization parameter. Data were taken at electron beam energies ranging from 3.40 to 5.75 GeV. The center of mass cross section was determined for 21 kinematics corresponding to Q2 of 1.90 and 2.35 GeV2 and the longitudinal, sigmaL, and transverse, sigmaT, cross sections were separated using the Rosenbluth technique at fixed W and t. The separated cross sections reveal a flat energy dependence at forward kaon angles not satisfactorily described by existing electroproduction models. Influence of the kaon pole on the cross sections was investigated by adopting an off-shell form factor in the Regge model which better describes the observed energy dependence of sigmaT and sigmaL.

Charged pion form factor betweenQ2=0.60and 2.45GeV2. I. Measurements of the cross section for the1H(e,e'π+)nreaction

Cross sections for the reaction 1H(e,e'π+)n were measured in Hall C at Thomas Jefferson National Accelerator Facility (JLab) using the high-intensity Continuous Electron Beam Accelerator Facility (CEBAF) to determine the charged pion form factor. Data were taken for central four-momentum transfers ranging from Q2=0.60 to 2.45 GeV2 at an invariant mass of the virtual photon-nucleon system of W=1.95 and 2.22 GeV. The measured cross sections were separated into the four structure functions σL,σT,σLT, and σTT. The various parts of the experimental setup and the analysis steps are described in detail, including the calibrations and systematic studies, which were needed to obtain high-precision results. The different types of systematic uncertainties are also discussed. The results for the separated cross sections as a function of the Mandelstam variable t at the different values of Q2 are presented. Some global features of the data are discussed, and the data are compared with the results of some model calculations for the reaction 1H(e,e'π+)n.16 MoreReceived 11 July 2008DOI:https://doi.org/10.1103/PhysRevC.78.045202©2008 American Physical Society

Theoretical treatments of fusion processes in collisions of weakly bound nuclei

We review the theoretical methods to evaluate fusion cross sections in collisions of weakly bound nuclei. We point out that in such collisions the coupling to the breakup channel leads to the appearance of different fusion processes. The extension of the coupled-channel method to coupling with the continuum is the most successful treatment for these collisions. However, evaluating separate cross section for each fusion process remains a very hard task.

Determination of the Pion Charge Form Factor atQ2=1.60and2.45 (GeV/c)2

The 1H(e,e'pi+)n cross section was measured at four-momentum transfers of Q2=1.60 and 2.45 GeV2 at an invariant mass of the photon nucleon system of W=2.22 GeV. The charged pion form factor (F(pi)) was extracted from the data by comparing the separated longitudinal pion electroproduction cross section to a Regge model prediction in which F(pi) is a free parameter. The results indicate that the pion form factor deviates from the charge-radius constrained monopole form at these values of Q2 by one sigma, but is still far from its perturbative quantum chromodynamics prediction.

Differential and integrated cross sections for excitation to the3s,3p, and3dstates of atomic hydrogen by electron impact below then=4threshold

Integrated cross sections for the electron-impact excitation of ground-state hydrogen to the 3s, 3p, and 3d final states have been calculated using propagating exterior complex scaling and convergent close-coupling methods at energies between the n=3 and 4 excitation thresholds. The calculations are in excellent agreement and demonstrate that exterior complex scaling methods can accurately reproduce the resonance structure and magnitude of the excitation cross sections below the ionization threshold. Measurements of the separate 3s, 3p, and 3d differential cross sections were made at 12.24 eV, and are consistent with both calculations within a total experimental uncertainty of about 35%.

Charged Pion Form Factor Determination in the Range of Q2 = 0.6 ~ 1.6 (GeV/c)2

Using the most recent differential cross section data for quasi-elastic scattering, the charged pion formation and its form factor is calculated in the energy range of at . The functional dependence of the charged pion form factor to the separated cross section is investigated and compared to the previously determined result.